A Novel Transformation Approach of Shared-link Coded Caching Schemes for Multiaccess Networks

This paper studies the multiaccess caching systems formulated by Hachem et al., including a central server containing
$N$
files connected to
$K$
cache-less users through an error-free shared link, and
$K$
cache-nodes, each equipped with a cache memory size of
$M$
files. Each user has access to
$L$
neighbouring cache-nodes with a cyclic wrap-around topology. The coded caching scheme proposed by Hachem et al. suffers from the case that
$L$
does not divide
$K$
, where the needed number of transmissions (a.k.a. load) is at most four times the load expression for the case where
$L$
divides
$K$
. Our main contribution is to propose a novel transformation approach to smartly extend the MN scheme to the multiaccess caching systems, such that the load expression of the scheme by Hachem et al for the case where
$L$
divides
$K$
, remains achievable in full generality. The resulting scheme has the maximum local caching gain (i.e., the cached contents stored at any
$L$
neighbouring cache-nodes are different such that each user can totally retrieve
$L M$
files from the connected cache-nodes) and the same coded caching gain as the related MN scheme. Moreover, our transformation approach can also be used to extend other coded caching schemes (satisfying some conditions) for the original MN caching systems to the multiaccess systems, such that the resulting scheme achieves the maximum local caching gain and the same coded caching gain as the considered caching scheme.